Fluid pressure cylinder and manufacturing method therefor

1. A fluid pressure cylinder, comprising:

a tubular cylinder tube;

a piston partitioning the interior of the cylinder tube into a head-side chamber and a bottom-side chamber; and

a piston rod coupled to the piston, wherein:

the piston rod is solid and internally provided with a head-side passage allowing communication between the head-side chamber and a working fluid pressure source and a bottom-side passage allowing communication between the bottom-side chamber and the working fluid pressure source;

the head-side passage is defined by a head-side shaft hole extending in an axial direction of the piston rod, a head-side outer hole connected to the head-side shaft hole and open on a part of the piston rod projecting from the cylinder tube and a head-side inner hole connected to the head-side shaft hole and open to the head-side chamber;

the head-side shaft hole includes an opening end open on the part of the piston rod projecting from the cylinder tube and a tip formed inside the piston rod;

the opening end of the head-side shaft hole is sealed by a sealing member;

the tip of the head-side shaft hole is located closer to the opening end of the head-side shaft hole than a part of the piston rod supporting the piston; and

the bottom-side passage is defined by a bottom-side shaft hole including an opening end open to the bottom-side chamber and extending in the axial direction of the piston rod beyond the part of the piston rod supporting the piston.

2. A fluid pressure cylinder, comprising:

a tubular cylinder tube;

a piston partitioning the interior of the cylinder tube into a head-side chamber and a bottom-side chamber; and

a piston rod coupled to the piston, wherein:

the piston rod is solid and internally provided with a head-side passage allowing communication between the head-side chamber and a working fluid pressure source and a bottom-side passage allowing communication between the bottom-side chamber and the working fluid pressure source;

the head-side passage is defined by a head-side shaft hole extending in an axial direction of the piston rod, a head-side outer hole connected to the head-side shaft hole and open on a part of the piston rod projecting from the cylinder tube and a head-side inner hole connected to the head-side shaft hole and open to the head-side chamber;

the head-side shaft hole includes an opening end open on the part of the piston rod projecting from the cylinder tube and a tip formed inside the piston rod;

the opening end of the head-side shaft hole is sealed by a sealing member;

the piston rod includes an annular eye portion on the part projecting from the cylinder tube;

an inner plug hole open on an inner peripheral surface of the eye portion is formed at the opening end of the head-side shaft hole; and

a plug is embedded as the sealing member into the inner plug hole.

3. A method for manufacturing a fluid pressure cylinder in which a head-side passage allowing communication between a head-side chamber and a working fluid pressure source and a bottom-side passage allowing communication between a bottom-side chamber and the working fluid pressure source are provided in a solid piston rod, comprising:

a head-side passage forming process of forming the head-side passage by a cutting tool inserted through a part of the piston rod projecting from a cylinder tube; and

a bottom-side passage forming process of forming the bottom-side passage by a cutting tool inserted through a part of the piston rod to be located in the cylinder tube.

4. The method for manufacturing the fluid pressure cylinder according to claim 3 , wherein:

the head-side passage forming process and the bottom-side passage forming process are performed in parallel.

5. The method according to claim 3 , further comprising:

a closing process of closing an opening end of the head-side passage at the part of the piston rod projecting from the cylinder tube, said closing process using a sealing member to close said opening end.

6. A fluid pressure cylinder, comprising:

a tubular cylinder tube;

a piston partitioning the interior of the cylinder tube into a head-side chamber and a bottom-side chamber; and

a piston rod coupled to the piston, wherein:

the piston rod is solid and internally provided with

a head-side passage allowing communication between the head-side chamber and a working fluid pressure source, and

a bottom-side passage allowing communication between the bottom-side chamber and the working fluid pressure source;

the head-side passage is defined by

a head-side shaft hole extending in an axial direction of the piston rod,

a head-side outer hole connected to the head-side shaft hole and opening on a part of the piston rod projecting from the cylinder tube, and

a head-side inner hole connected to the head-side shaft hole and opening to the head-side chamber;

the head-side shaft hole includes

an opening end open on the part of the piston rod projecting from the cylinder tube, and

a tip formed inside the piston rod;

the opening end of the head-side shaft hole is sealed by a sealing member;

the bottom-side passage is defined by

a bottom-side shaft hole extending in the axial direction of the piston rod, and

a bottom-side outer hole connected to the bottom-side shaft hole and opening on another part of the piston rod projecting from the cylinder tube; and

the bottom-side shaft hole includes

an opening end open in the bottom-side chamber, and

a tip formed inside the piston rod.